#序列
my_list=[1,2,3,4,5]
new_list=my_list[:4]
print(new_list)

num_list=[34,78,90,67,12]
num1_list=num_list[::2]
print(num1_list)
zt_list=[24.65,68,94,73]
zt1_list=zt_list[:4:2]
print(zt1_list)